灰葡萄孢胞壁降解酶对番茄植株致病作用的分析

Analysis on the pathogenicity of the cell wall degradation enzymes produced by Botrytis cinerea to tomato plant

灰葡萄孢(Botrytis cinerea)是一种寄主范围多达200多种植物的病菌,其在致病过程中能产生多种胞壁降解酶,包括多种果胶酶和纤维素酶。用果胶酶和纤维素酶处理番茄叶片,产生相似于病害症状的水渍状腐烂斑,能破坏细胞超微结构,使叶绿体、线粒体等细胞器解体;分生孢子萌发和菌丝生长中能产生多种酶类,其中多聚半乳糖醛酸甲基水解酶(PMG)活性较高,且分生孢子萌发60 h后该酶仍具有活性。在番茄植株不同部位形成的病斑中均能检测到PMG,病斑褐色部位的PMG活性明显高于黄色部位。纤维素酶活性除了在分生孢子萌发阶段和果实病斑中未能检出外,在菌丝培养液和叶片病斑的褐色部分均能检测到该酶活性。病菌果胶酶和纤维素酶活性与病菌致病力的相关性测验表明,两类酶与致病力均为正相关,相关系数分别为0.362 3和0.105 7。根据上述结果分析,果胶酶和纤维素酶均能对寄主植物造成伤害,在病菌致病过程中有增加病菌毒力的作用。

Botrytis cinerea,a pathogen that causes diseases in over 200 plant species,secretes a number of cell wall degradation enzymes that have been suggested to be involved in pathogenesis.The pectinase coulde cause leaves maceration or rot,and lead to the chloroplast and mitochondrion of leaf cell collapse when the leaves treated with pectinase of B.cinerea.Several kinds of cell wall degradation enzyme could be secreted to extracellular by B.cinerea at the conidial germination and hyphal growth stages and the polymethylgalacturonase（PMG） exhibited higher activity among these cell wall degradation enzymes,in which PMG could still be detected at 60 h after the conidial germination.The PMG could be detected in the tissues of disease spots at different parts of tomato plant caused by B.cinerea and the PMG activity was higher in the brown area of the disease spots on the tomato leaf than that in the yellow area that circled the brown area.The cellulase activity could be detected in the culture filtrate of the pathogenic fungal mycelium and in the brown necrosis area of disease spots on the leaves that were inoculated with conidia of B.cinerea.Whereas cellulase did not appear in the filtrate of conidial germination and in the disease spots of fruits.There was a feeblish positive correlation between the ability of the pathogen producting pectinase and cellulase and the virulence of B.cinerea to tomato plant（R2=0.362 3,0.105 7 respectively）.The present study revealed that the pectinase and cellulase of B.cinerea coulde injure tomato plant and played a role in enhancing virulence of B.cinerea.